[High grade (B) oligodendroglioma. Concerns and pitfalls in the intraoperative examination of smears]

According to the Ste Anne hospital classification and grading system of oligodendrogliomas the presence of contrast enhancement on MRI and/or the presence of an histological endothelial hyperplasia are correlated with a pejorative prognosis (high grade or grade B). Surgical tumoral exerese and adjuvant chemo or radiotherapy are indicated. When clinical and radiological aspects are typical the extemporaneous diagnosis of oligodendroglioma on smear is usually easy (1). In case of atypical forms: unusual localization or cytological appearance, especially with a small cell hyperchromatic undifferenciated tumor few diagnostic hypothesismay be considered. Four cerebellar tumors are presented with relevant and differential cytological diagnostic criteria. A comparative study between clinical and radiological aspects of medulloblastoma, primitive lymphoma, undifferenciated small cell lung carcinoma, and grade B oligodendroglioma is presented.